Meeting Abstract

22.2  Jan. 5  Metabolic rate governs rates of genotypic and phenotypic evolution MCCOY, M. W.*; GILLOOLY, J. F.; ALLEN, A. P.; University of Florida; University of Florida; NCEAS mmccoy@zoo.ufl.edu

Determining the relative importance of neutral versus adaptive processes in shaping rates of phenotypic evolution is a central aim of evolutionary biology. Many evolutionary biologists, while agreeing that most changes to the genotype are neutral, would argue that most changes to the phenotype are adaptive. However, the relative importance of neutral mutation versus natural selection in driving phenotypic change has been difficult to quantify. Here we apply the body size- temperature model of molecular evolution proposed by Gillooly et al. (2005) to address the importance of neutral processes in controlling rates of phenotypic evolution. Gillooly et al. (2005) showed that neutral rates of DNA evolution are proportional to mass-specific metabolic rate. In this study we show that for both mitochondrial and nuclear genes, non-neutral rates of DNA evolution, as well as rates of amino acid (i.e., phenotypic) evolution show the same size-and temperature dependence as neutral molecular evolution. This indicates that rates of phenotypic evolution, like neutral evolution, are directly proportional to mass-specific metabolic rate. More generally, these results suggest that the primary controls on individual metabolic rate (i.e., size and temperature) may also constrain the overall rate of evolution in organisms through their effects on mutation rate. Ultimately, our hope is that this work can be extended to better understand rates of speciation and patterns in biodiversity.